In general, content addressable memory (CAM) cells are used in combination with a read/write memory (RWM) cell to form an associative memory for use in caches, memory management units, and the like. Examples of such memories are shown in U.S. Pat. Nos. 3,229,255, 3,235,845, 3,239,818, 4,296,475, 4,404,653, 4,473,878. Other examples are discussed in James T. Koo, Integrated-Circuit Content-Addressable Memories, IEEE Journal of Solid-State Circuits, vol. SC-5, No. 5, pp 208-215, October 1970; Hiroshi Kodata, et al., An 8 Kb Content-Addressable and Reentrant Memory, IEEE International Solid-State Circuits Conference 1985 Digest of Technical Papers, pp 42-43, February 1985 (which is also in IEEE Journal of Solid State Circuits, vol. SC-20, No. 5, pp 951-957). In some of these memories, the bits stored in certain subsets or "fields" of the CAM cells in each word are selectively masked in response to a mask signal of some suitable form. In general, significant additional circuitry is required in order to provide this masking function. In addition to increasing the size, complexity and power dissipation of the memory, the masking circuitry often required the CAM cells of the masked and masking bits to be significantly different, contributing to layout difficulties of the memory.